What is Geology?

Definition
Geology is the scientific study of the Earth, its materials, and the processes acting upon them.
Earth’s Relationship to the Universe
Understanding Earth’s formation, its position in the solar system, and its interactions with cosmic forces.
Earth’s History
Examining changes over the past 4.5 billion years, including the formation of continents, oceans, and life.
Geological Processes
Investigating internal processes (e.g., plate tectonics, volcanic activity) and external processes (e.g., erosion, weathering) that shape the Earth’s surface.

Earth Over Time, Source: NASA

What is Geology? (continue)

Finding valuable natural resources such as soil, water, metals, industrial minerals, and energy
Understand the evolution of our environment and the life within it.
Minimize our risks from Natural hazards, earthquakes, volcanoes, slope failures, and damaging storms.
Understand the causes of the climate change.
Recognize how our activities have altered the environment.
Use our knowledge of Earth to understand other planets in our solar system

Source: Jain, S., 2014. Fundamentals of physical geology. New Delhi, India: Springer India.

Branch	Area of Study	Related Science
Physical Geology
Endogenous Geology	Geotectonics (Earth’s crust, condition, and deformation)	Physics
	Metamorphism (Transformation of existing rocks)
	Magmatism (Interior of Earth)
	Volcanism (Volcanoes)
	Seismology (Earthquakes)	Physics
Exogenous Geology
	Weathering and Mass Wasting (Alteration of sediments)	Chemistry
	Oceanography (Oceans and seas)
	Marine Geology (Ocean margin and floor)	Biology
	Hydrogeology (Water resources)
	Glaciology (Glaciers)
	Limnology (Bogs and lakes)
	Geomorphology (Landforms)
	Structural Geology (Rock deformation)	Physics
	Sedimentology (Sediment deposition)
	Mineralogy (Minerals)
Economic Geology
	Minerals and energy resources	Chemistry
	Petroleum Geology (Hydrocarbons)
	Coal Geology (Coal)
Geochemistry		Chemistry
	Chemistry of Earth
	Isotope Geology (Radioactive elements)
Historical Geology
	Earth’s evolutionary history
	Geochronology (Time and history of Earth)	Astronomy
	Stratigraphy (Layered sediments and correlation)
	Paleontology (Fossils)	Biology
	Micropaleontology (Microorganisms)
	Paleoecology (Ancient ecology and environment)	Biology
	Paleoclimatology (Ancient climate)
	Paleography (Ancient geographic features and locations)
	Paleomagnetism (Earth’s magnetic field)	Physics
Applied Geology
	Environmental Geology (Environment)	Chemistry, Biology
	Engineering Geology (Geological hazards, bridges, dams, etc.)	Engineering
	Hydrogeology (Water resources)
	Geophysics (Earth’s interior)	Physics

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Origin of the Universe: The Universe began ~13.8 billion years ago from a hot, dense singularity.
Expansion: Universe has been expanding since, leading to the formation of galaxies, stars, and planets.

Planetary Formation: Proposed that planets formed from debris after a comet collided with the Sun.
Early Hypothesis: An initial speculative idea without extensive supporting evidence.

Solar System Formation: Solar System formed from a rotating cloud of gas and dust (nebula).
Gravitational Collapse: Nebula collapsed under gravity, forming the Sun at the center and planets from surrounding material.
Widely Accepted: Strongly supported by observations.

Alternative Cosmology: Universe has no beginning or end; constant density with continuous creation of matter.
Opposition to Big Bang: Largely rejected due to lack of evidence compared to Big Bang Theory.

Refinement of Nebular Theory: Incorporates physics and chemistry to explain the formation of planets.
Protoplanetary Disk: Planets formed from the condensation and accretion of solid particles within a disk around the Sun.
Current Understanding: Supported by modern astronomical observations and models.